Transmission and control with shift engagement timing devices

ABSTRACT

A transmission and control in which the transmission has three mechanical gear ratios which are selectively established by the control. The control provides through the use of a plurality of fluid restrictions one engagement time of the intermediate ratio control device during an upshift from the first ratio to the second ratio and another engagement time of the intermediate ratio control device during a downshift from third ratio to second ratio. The control also provides a bypass valve so that the disengagement time of the intermediate ratio control device is not affected by the fluid restrictions during a second to third or second to first ratio change.

United States Patent 1 1 3,754,483

Edmunds Aug. 28, 1973' [54] TRANSMISSION AND CONTROL WITH 3,688,6089/1972 Leach 74/753 X 5 1" ENGAGEMENT TIMING DEVICES 3,691,872 9/1972Schaefer et al. 74/869 X [75] Inventor: John 0. Edmunds, Indianapolis,Ind.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Nov. 11, 1971 [21] Appl. No.: 197,903

[52] U.S. Cl 74/753, 74/868, 74/DIG. 1, 192/109 F [51] Int. C1.Fl6h5/18, Fl6h 57/10, Fl6d 67/04 [58] Field of Search 74/863, 864, 867,74/868, 869, 753, DIG. 1; 192/109 F [56] References Cited UNITED STATESPATENTS 3,625,090 12/1971 Chana 74/869 X 3,651,714 3/1972 Ohya et al.74/867 3,505,907 4/1970 Fox et al 74/753 3,509,784 5/1970 Mahoney 74/8693,613,484 10/1971 Pierce et a1 74/869 Primary Examiner-Charles J. MyhreAssistant Examiner-Thomas C. Perry Att0mey--W. E. Finken, D. F. Schereret a1.

[5 7] ABSTRACT A transmission and control in which the transmission hasthree mechanical gear ratios which are selectively established by thecontrol. The control provides through the use of a plurality of fluidrestrictions one engagement time of the intermediate ratio controldevice during an upshift from the first ratio to the second ratio andanother engagement time of the intermediate ratio control device duringa downshift from third ratio to second ratio. The control also providesa bypass valve so that the disengagement time of the intermediate ratiocontrol device is not affected by the fluid restrictions during a secondto third or second to first ratio change.

8 Claims, 1 Drawing Figure I 2.11 RAT-IO TRIMMER Iss RATIO TRIMMERTRANSMISSION AND CONTROL WITH SHIFT ENGAGEMENT TIMING DEVICES Thisinvention relates to automatic transmissions and controls and moreparticularly to transmissions and controls wherein the engagement timeof one ratio control device is varied.

In a transmission having three or more selectively establishable gearratios it is desirable to control the engagement time of theintermediate ratios at different values depending upon whether thetransmission isupshifting to the intermediate ratio or downshifmg to theintermediate ratio. Prior art controls have generally utilized a trimmervalve alone or in combination with a single fluid restriction to controlthe engagement time of the intermediate ratio. This type of controlprovides a single engagement time whether an upshift or downshaft to theintermediate ratio is being accomplished. In these types of controls therestriction is therefore a compromise between the ideal engagement timesand is therefore not the most desirable.

The present invention in the preferred embodiment utilizes a pair offluid restrictions which are disposed in parallel flow relationship inthe feed passage for the intermediate ratio control device. One of therestrictions is controlled by the trimmer valve which controls theengagement pressure of the low ratio in such a manner that fluid passesthrough this restriction during a low to intermediate shift change andthe restriction is blocked from fluid passage during a third or highratio to intermediate ratio shift change. The other fluid restriction iscontinually open in the intermediate engagement passage. Thus, om a lowto intermediate shift change both restrictions function to control fluidflow to the intermediate engagement device while on a high tointermediate ratio change only one of the restrictions controls fluidflow to the intermediate ratio control device.

A one way valve such as a check valve is also disposed in theintermediate feed passage in parallel with the fluid restrictions sothat on disengagement the intermediate ratio control device is freelyopen to exhaust. v

It is an object of this invention to provide in an im provedtransmission and control, in which three drive ratios are available, oneengagement rate during an upshift to the intermediate ratio and anotherengagement rate during a downshift to the intermediate ratio.

It is another object of this invention to provide in an improvedtransmission and control having at least three drive ratios, valve meansfor controlling the amount of restriction in the intermediate engagementpassage to provide less restriction during an upshift to theintermediate ratio than is provided during a downshift to theintermediate ratio.

It is another object of this invention to provide in an improvedtransmission and control having at least three drive ratios a trimmervalve for the low speed ratio which trimmer valve functions to controlthe restriction of fluid feed to the intermediate ratio at one levelduring an upshift to the intermediate ratio and at a second level duringa downshift to the intermediate ratio and a bypass control for therestrictions to permit free exhaust of the intermediate ratio duringdisengagement thereof.

Other objects and advantages of the present invention will be moreapparent from the following description and drawing of the preferredembodiment in which is shown in diagrammatic form a three speedtransmission and control valving.

Referring to the drawing there is shown a planetary transmission havingan input shaft 10 adapted to be driven by a conventional vehicle engineand torque converter 11. The input shaft 10 drives a hub 12 which formsa portion of a forward clutch l4 and a directreverse clutch 16. Theclutch 14 is drive connected to an intermediate shaft 18 which is driveconnected via a hub 20 with a ring gear 22. The clutch 16 is driveconnected to another intermediate shaft 24 which is drive connected to apair of sun gears 26 and 28. The intermediate shaft 24 is also driveconnected to an intermediate brake 30.

The sun gear 26 and ring gear 22 are in mesh with a planet gear 32rotatably mounted on a planet carrier 34 which is connected through ahub 36 to a transmission output shaft 38. The sun gear 28 meshes with aplanet gear 40 which also meshes with a ring gear 42 which is also driveconnected to the hub 36 and output shaft 38. The planet gear 40 isrotatably mounted on a planet carrier 44 which is drive connected to alow brake 46.

The clutch l6 and brakes 30 and 46 are fluid operated type frictiondevices which are controlled by pistons 48, 50 and 52 respectively.

During operation of the transmission the clutch l4 and the brake 52 areengaged to provide a first or low gear ratio between the input shaft I0of the output shaft 38. To establish intermediate or second gear ratiothe brake 52 is disengaged while the brake 50 is engaged and the clutch14 remains engaged. To establish third gear or high ratio the brake 50is disengaged while the clutch 16 is engaged and the clutch 14 remainsengaged. A reverse ratio may be established by engaging clutch l6 andbrake 46 while the other clutches and brakes are disengaged.

The pistons 48 and 52 are in fluid communication with a manual shiftvalve 54 via third clutch speed passage 56 and low brake feed passage58. The piston 50 of the intermediate brake 30 is in fluid communicationwith an intermediate feed passage 60 which is in fluid communicationwith an intermediate engagement passage 62 through a pair ofrestrictions 64 and 66 and a one way check valve 68 which permits flowfrom passage 60 to passage 62 through a restriction 69 but preventsreverse flow. The intermediate engagement passage 62 is operativelyconnected with the shift valve 54. The restriction 64 is controlled inits fluid communication with the intermediate engagement passage 62 by afirst ratio trimmer valve, generally designated 70. The intermediatefeed passage 60 is also in fluid communication with a second ratiotrimmer valve 72.

Fluid pressure for the control system is supplied by a positivedisplacement fluid pump 74 which draws fluid from a reservoir 76 throughan inlet passage 78 and delivers fluid pressure through a main passage80 to the shift valve 54. Fluid pressure in the main passage 80 iscontrolled by a conventional pressure regulator valve 82 which bypassesexcess fluid from the main passage 80 through passage 84 to thereservoir 76.

The shift valve 54 is shown as a manual type shift control valve whichis movable to a plurality of positions to control the level of fluidpressure from the pump 74 to the low brake feed passage 58, theintermediate engagement passage 62 and the third clutch feed passage 56.The shift valve 54 may be similar in construction to the manual shiftvalve shown in the US.

Pat. to Schaefer No. 3,459,071 issued Aug. 5, 1969 or any of the otherwell known and available shift valve mechanisms. The shift valve 54 canalso be replaced by an automatic shift control system such as that shownin the U.S. Pat. to Mahoney No. 3,509,784 issued May 5, 1970 and stillbe consistent with the present invention.

The first ratio trimmer valve 70 includes a pressure regulator plug 86having a small diameter land a and a larger diameter land b slidablydisposed in a stepped valve bore 88, a bias plug 90 having equaldiameter lands a and b and an annular recess portion 92 therebetween, abias spring 94 and a stop member 96. The valve bore 88 is in fluidcommunication with the low brake feed passage 58, which supplies fluidto the end of the plug 86 through a passage 97 formed in the plug 86,the intermediate engagement passage 62 through a pair of diametricallyopposed ports 101 and 103 and two exhaust passages 98 and 99. In theposition shown in land b the bias plug 90 prevents fluid communicationbetween the intermediate engagement passage 62 and the restriction 64.

When the shift valve 54 is moved to provide fluid communication betweenmain passage 80 and the low brake feed passage 58 the fluid pressure isalso transmitted to the diameter a of the regulator plug 86 of the firstratio trimmer valve 70. When the pressure is introduced to the trimmervalve 70, the plug 86 will move in the bore 88 against the bias force ofspring 94 to permit excess fluid to be exhausted through passage 98. Atthe same time fluid pressure begins to flow through a restriction 100 inthe plug 86 to a chamber 102 between the plugs 86 and 90 to cause plug90 to move against spring 94. The movement of plug 90 increases theforce of spring 94 and the trim pressure increases in proportion. As theplug stops on stop 96 the pressures in 97 and 102 equate and thepressure on the larger area 102 closes the regulating valve 97. Thefluid pressure in passage 58 will increase and the plug 90 will movetoward the stop 96. The initial movement of plugs 97 and 90 toregulating height, as above, opens passage 62 to restriction 64 throughthe annular recessed portion 92 between lands a and b and this remainsopen as long as the first ratio is engaged.

The second ratio trimmer valve 72 has a regulator piston 104 slidablydisposed in a valve bore 106, a bias plug 108 also slidably disposed inthe valve bore 106, a bias spring 110 compressed between the bias plug108 and one end of valve bore 106 and a light bias spring 1 11 betweenpiston 104 and plug 108. The valve bore 106 is in fluid communicationwith the intermediate feed passage 60 and with two exhaust passages 112and 114. The regulator piston 104 has a restricted passage 116 whichadmits fluid between the piston 104 and the plug 108. When theintermediate feed passage 60 is pressurized the regulator piston 104will move in the bore 106 against the bias spring 110 until the exhaustpassage [12 is opened by the piston 104. Also during this time fluidwill flow through the restricted passage 106 between piston 104 and plug108 to move plug 108 against regulator spring 106. As the plug movesagainst spring 106 the regulated pressure increases until plug reachesstop 118. At this time the force of spring 111 and the pressure biasforce between plugs 108 and 104 become grounded on stop 118. These areadditives and greater than the regulated pressure bias on plug 104.Thus, the plug 104 moves to shut off regulation and the line 60 pressureimmediately rises to equal main pressure.

When the brake 46 is released the regulator plug 86 remains in theposition shown and the bias plug will begin to move from the stop96.'The time required for the plug 90 to move is determined by therestriction and the force in spring 94. This time will be longer thanthe time required to complete the first to second upshift so that theintermediate shift passage 62 will be opened between lands a and b ofplug 90 during the upshift.

The second ratio trimmer valve 72 is operable during a l-2 upshift and a32 downshift. The check valve 68 and restriction 69 permit restrictedexhaust of the intermediate brake 30 and cooperates with restriction 66during a 2-3 upshift and with restrictions 64 and 66 during a 2-1downshift. The trimmer valve 72 returns to the position shown on a shiftfrom second in preparation for a subsequent shift to second. Therestrictions 64, 66 and 69 cooperate to provide more rapid disengagementof the brake 30 during a 2-1 downshift than during a 2-3 upshift. Duringa l-2 upshift the first ratio trimmer valve will have been operated tocommunicate the passage 62 with the restriction 64 between the lands aand b of the plug 90 such that both restrictions 64 and 66 will beavailable to feed the intermediate feed passage 60 during a 1-2 upshift.During a 32 downshift, however, the first ratio trimmer valve 70 will bein the position shown so that the intermediate feed passage 60 will befed from intermediate engage passage 62 through restriction 66 alone.Therefore, the intermediate brake 30 will be engaged more rapidly duringa 1-2 upshift and will be engaged slowly during a 32 downshift. Thispermits the engine to be rapidly decelerated during an upshift andpermits the engine to be slowly accelerated during a downshift thusproviding more desirable shift timing during the various changes of gearratios in the transmission.

While the invention described-is a transmission having three speedratios it can be used in transmissions having more than three speedratios. If, for example, the invention is used with a four speedtransmission, the second ratio trimmer valve 72 would be constructedsimilar to the first ratio trimmer valve 70 so that a pair ofrestrictions placed in parallel in the third ratio feed line, could becontrolled during a 2-3 upshift and a 4-3 downshift. The invention canbe expanded to transmissions having more ratios by using restrictions inparallel in the drive establishing device feed lines in the intermediateratios and utilizing the trimmer valve for the next lower ratio tocontrol fluid flow through the restrictions.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

l. A transmission and control comprising in combination, planetarygearing means; first, second and third fluid operated selectivelyoperable drive ratio establishing means operatively connected with saidplanetary gearing means for selectively establishing first, second andthird drive ratios therein; a source of fluid pressure; shift valvemeans in fluid communication with said source and said drive ratioestablishing means for selectively engaging and disengaging said driveratio establishing means; first timing control means in series with saidshift valve means and said second drive ratio establishing means andoperatively connected in fluid communication with said first drive ratioestablishing means for controlling the engagement time of said seconddrive ratio establishing means during the interchange from said first tosaid second drive ratio establishing means; and second timing controlmeans in parallel with said first timing control means and cooperatingtherewith for controlling the engagement time of said second drive ratioestablishing means during the first to second drive ratio establishingmeans interchange, and being operable to control the engagement time ofsaid second drive ratio establishing means during the interchange fromsaid third to second drive ratio establishing means; said first timingcontrol means being inoperable during said third to second drive ratioestablishing means interchange.

2. A transmission and control comprising in combi nation, planetarygearing means; first, second and third fluid operated selectivelyoperable drive ratio establishing means operatively connected with saidplanetary gearing means for selectively establishing first, second andthird drive ratios therein; a source of fluid pressure; shift valvemeans in fluid communication with said source and said drive ratioestablishing means for selectively engaging and disengaging said driveratio establishing means; first restriction means in series with saidshift valve means and said second drive ratio establishing means;trimmer valve means for controlling pressure in said first drive ratioestablishing means having a member connected in fluid communication withsaid source and said first restriction means for permitting fluid flowthrough said first restriction means during the interchange from saidfirst to said second drive ratio establishing means and preventing fluidflow through said first restriction during a third to second drive ratioestablishing means interchange; and second restriction means in parallelwith said first restriction means and cooperating therewith forcontrolling the engagement time of said second drive ratio establishingmeans during the first to second drive ratio establishing meansinterchange, and being operable to control the engagement time of saidsecond drive ratio establishing means during the interchange from saidthird to second drive ratio establishing means.

3. A transmission and control comprising in combination, multi-speeddrive ratio means for providing low, intermediate and high drive ratioshaving a plurality of fluid operated means for controlling said driveratios; a source of fluid pressure; shift valve means for selectivelyconnecting said source with said fluid operated means; a pair of flowrestriction means in parallel for controlling fluid flow between saidsource and said fluid operated means controlling said intermediate driveratio; and pressure control means for controlling fluid pressure in oneof said fluid operated means and including moveable means responsive tofluid pressure in said one of said fluid operated means for controllingflow to said flow restriction means for permitting flow through bothsaid flow restriction means during a low to intermediate drive ratiointerchange and for permitting flow through only one of said restrictionmeans during a high to intermediate drive ratio interchange to controlthe engagement time of said intermediate ratio.

4. A transmission and control comprising in combination, planetarygearing means; first, second and third fluid operated selectivelyoperable drive ratio establishing means operatively connected with saidplanetary gearing means for selectively establishing first, second andthird drive ratios therein; a source of fluid pressure; shift valvemeans in fluid communication with said source and said drive ratioestablishing means for selectively engaging and disengaging said driveratio establishing means; first timing control means in series with saidshift valve means and said second drive ratio establishing means andoperatively connected in fluid communication with said first drive ratioestablishing means for controlling the engagement time of said seconddrive ratio establishing means during the interchange from said first tosaid second drive ratio establishing means; second timing control meansin parallel with said first timing control means and cooperatingtherewith for controlling the engagement time of said second drive ratioestablishing means during the first to second drive ratio establishingmeans interchange, and being operable to control the engagement time ofsaid second drive ratio establishing means during the interchange fromsaid third to second drive ratio establishing means; said first timingcontrol means being inoperable during said third to second drive ratioestablishing means interchange; and one way valve means for permittingfree exhaust of said second drive ratio establishing means during thesecond ratio to first ratio interchange and the second ratio to thirdratio interchange.

5.. A transmission and control comprising in combination, planetarygearing means; first, second and third fluid operated selectivelyoperable drive ratio establishing means operatively connected with saidplanetary gearing means for selectively establishing first, second andthird drive ratios therein; a source of fluid pressure; shift valvemeans in fluid communication with said source and said drive ratioestablishing means for selectively engaging and disengaging said driveratio establishing means; first restriction means in series with saidshift valve means and said second drive ratio establishing means;trimmer valve means for controlling pressure in said first drive ratioestablishing means including a regulator valve means for controllingpressure in said first drive ratio establishing means and a valve memberhaving a pair of spaced lands connected in fluid communication betweensaid source and said first restriction means and being movable inresponse to fluid pressure regulated by the regulator valve means forsaid first drive ratio establishing means to one position to permitfluid flow between said lands to said first restriction means during theinterchange from said first to said second drive ratio establishingmeans and being movable to another position to align one of said landswith flow from said source to prevent fluid flow to said firstrestriction during a third. to second drive ratio establishing meansinterchange; and second restriction means in parallel with said firstrestriction means and cooperating therewith for controlling theengagement time of said second drive ratio establishing means during thefirst to second drive ratio establishing means interchange, and beingoperable to control the engagement time of said second drive ratioestablishing means during the interchange from said third to seconddrive ratio establishing means.

6. A transmission and control comprising in combination, planetarygearing means; first, second and third fluid operated selectivelyoperable drive ratio establishing means operatively connected with saidplanetary gearing means for selectively establishing first, second andthird drive ratios therein; a source of fluid pressure; shift valvemeans in fluid communication with said source and said drive ratioestablishing means for selectively engaging and disengaging said driveratio establishing means; first timing control means in series with saidshift valve means and said second drive ratio establishing means forcontrolling the engagement time of said second drive ratio establishingmeans during the interchange from said first to said second drive ratioestablishing means; trimmer valve means in fluid communication with saidsource and said first drive ratio establishing means including valvemeans having a pair of spaced lands and being movable to one position inresponse to fluid pressure in said first drive ratio establishing meansto permit flow between said lands from said source to said first timingcontrol means, and to another position when said first drive ratioestablishing means is inoperative to align one of said lands betweensaid source and said first timing control means to prevent fluid flowfrom said source to said first timing control means; second timingcontrol means in parallel with said first timing control means andcooperating therewith for controlling the engagement time of said seconddrive ratio establishing means during the first to second drive ratioestablishing means interchange, and being operable to control theengagement time of said second drive ratio establishing during theinterchange from said third to second drive ratio establishing means;and one way valve means for permitting free exhaust of said second driveratio establishing means during the second ratio to first ratiointerchange and the second ratio to third ratio interchange.

7. A transmission and control comprising in combination; multispeeddrive ratio means for providing low, intermediate and high drive ratiosand a plurality of fluid operated means selectively operated forestablishing said drive ratios; a source of fluid pressure; shift valvemeans, including low, intermediate and high passage means connected tosaid fluid operated means, for selectively exhausting and connectingsaid source to said low, intermediate and high passage means and saidfluid operated means to selectively disestablish and establish said low,intermediate and high drive ratios; variable flow restriction means insaid intermediate passage means having a low and a high restrictionposition controlling the time of establishment of said intermediatedrive ratio; trimmer regulator valve means peratively connected toanother of said passage means having a normal position when said anotherof said passage means is conditioned to disestablish another drive ratioand operative in response to change of fluid pressure in said another ofsaid passage means to variably regulate the pressure in said another ofsaid passage means for gradual establishment of said another drive ratiowhile moving to a terminal position and to remain in said terminalposition while said another drive ratio remains established andoperative during disestablishment of said another drive ratio to slowlymove from said terminal position to said normal position and operativelyconnected to said variable flow restriction means and responsive to saidmovement between said terminal and normal positions to provide said highrestriction during a high to intermediate interchange and said lowrestriction during a low to intermediate interchange.

8. A transmission and control comprising in combination; multispeeddrive ratio means for providing low, intermediate and high drive ratiosand a plurality of fluid operated means selectively operated forestablishing said drive ratios; a source of fluid pressure; shift valvemeans, including low, intermediate and high passage means connected tosaid fluid operated means, for selectively connecting said source tosupply fluid to said low, intermediate and high passage means and saidfluid operated means to selectively establish said low, intermediate andhigh drive ratios in a predetermined time period and selectivelyexhausting fluid from said low, intermediate and high passage means andsaid 1 fluid operated means to selectively disestablish said low,intermediate and high drive ratios; variable flow restriction means insaid intermediate passage means having a low and a high restrictionposition controlling the rate of flow to and the time of establishmentof said intermediate drive ratio; trimmer regulator valve meansoperatively connected to another of said passage means having a normalposition when said another of said passage means is exhausted todisestablish another drive ratio and operative in response to the supplyof fluid pressure in said another of said passage means to regulate thepressure in said another of said passage means at gradually increasingpressures for gradual establishment of said another drive ratio whilemoving to a terminal position and to remain in said terminal positionproviding full pressure while said another drive ratio remainsestablished and operative on exhaust of pressure in said another passagemeans for disestablishment of said another drive ratio to slowly movefrom said terminal position to said normal position in a time period atleast as large as said predetermined time period for establishment ofsaid intermediate ratio and operatively connected to said variable flowrestriction means and responsive to said movement between said terminaland normal positions to provide said high restriction during a high tointermediate interchange and said low restriction during a low tointermediate interchange.

1. A transmission and control comprising in combination, planetarygearing means; first, second and third fluid operated selectivelyoperable drive ratio establishing means operatively connected with saidplanetary gearing means for selectively establishing first, second andthird drive ratios therein; a source of fluid pressure; shift valvemeans in fluid communication with said source and said drive ratioestablishing means for selectively engaging and disengaging said driveratio establishing means; first timing control means in series with saidshift valve means and said second drive ratio establishing means andoperatively connected in fluid communication with said first drive ratioestablishing means for controlling the engagement time of said seconddrive ratio establishing means during the interchange from said first tosaid second drive ratio establishing means; and second timing controlmeans in parallel with said first timing control means and cooperatingtherewith for controlling the engagement time of said second drive ratioestablishing means during the first to second drive raTio establishingmeans interchange, and being operable to control the engagement time ofsaid second drive ratio establishing means during the interchange fromsaid third to second drive ratio establishing means; said first timingcontrol means being inoperable during said third to second drive ratioestablishing means interchange.
 2. A transmission and control comprisingin combination, planetary gearing means; first, second and third fluidoperated selectively operable drive ratio establishing means operativelyconnected with said planetary gearing means for selectively establishingfirst, second and third drive ratios therein; a source of fluidpressure; shift valve means in fluid communication with said source andsaid drive ratio establishing means for selectively engaging anddisengaging said drive ratio establishing means; first restriction meansin series with said shift valve means and said second drive ratioestablishing means; trimmer valve means for controlling pressure in saidfirst drive ratio establishing means having a member connected in fluidcommunication with said source and said first restriction means forpermitting fluid flow through said first restriction means during theinterchange from said first to said second drive ratio establishingmeans and preventing fluid flow through said first restriction during athird to second drive ratio establishing means interchange; and secondrestriction means in parallel with said first restriction means andcooperating therewith for controlling the engagement time of said seconddrive ratio establishing means during the first to second drive ratioestablishing means interchange, and being operable to control theengagement time of said second drive ratio establishing means during theinterchange from said third to second drive ratio establishing means. 3.A transmission and control comprising in combination, multi-speed driveratio means for providing low, intermediate and high drive ratios havinga plurality of fluid operated means for controlling said drive ratios; asource of fluid pressure; shift valve means for selectively connectingsaid source with said fluid operated means; a pair of flow restrictionmeans in parallel for controlling fluid flow between said source andsaid fluid operated means controlling said intermediate drive ratio; andpressure control means for controlling fluid pressure in one of saidfluid operated means and including moveable means responsive to fluidpressure in said one of said fluid operated means for controlling flowto said flow restriction means for permitting flow through both saidflow restriction means during a low to intermediate drive ratiointerchange and for permitting flow through only one of said restrictionmeans during a high to intermediate drive ratio interchange to controlthe engagement time of said intermediate ratio.
 4. A transmission andcontrol comprising in combination, planetary gearing means; first,second and third fluid operated selectively operable drive ratioestablishing means operatively connected with said planetary gearingmeans for selectively establishing first, second and third drive ratiostherein; a source of fluid pressure; shift valve means in fluidcommunication with said source and said drive ratio establishing meansfor selectively engaging and disengaging said drive ratio establishingmeans; first timing control means in series with said shift valve meansand said second drive ratio establishing means and operatively connectedin fluid communication with said first drive ratio establishing meansfor controlling the engagement time of said second drive ratioestablishing means during the interchange from said first to said seconddrive ratio establishing means; second timing control means in parallelwith said first timing control means and cooperating therewith forcontrolling the engagement time of said second drive ratio establishingmeans during the first to second drive ratio establishing meansinterchange, and being operAble to control the engagement time of saidsecond drive ratio establishing means during the interchange from saidthird to second drive ratio establishing means; said first timingcontrol means being inoperable during said third to second drive ratioestablishing means interchange; and one way valve means for permittingfree exhaust of said second drive ratio establishing means during thesecond ratio to first ratio interchange and the second ratio to thirdratio interchange.
 5. A transmission and control comprising incombination, planetary gearing means; first, second and third fluidoperated selectively operable drive ratio establishing means operativelyconnected with said planetary gearing means for selectively establishingfirst, second and third drive ratios therein; a source of fluidpressure; shift valve means in fluid communication with said source andsaid drive ratio establishing means for selectively engaging anddisengaging said drive ratio establishing means; first restriction meansin series with said shift valve means and said second drive ratioestablishing means; trimmer valve means for controlling pressure in saidfirst drive ratio establishing means including a regulator valve meansfor controlling pressure in said first drive ratio establishing meansand a valve member having a pair of spaced lands connected in fluidcommunication between said source and said first restriction means andbeing movable in response to fluid pressure regulated by the regulatorvalve means for said first drive ratio establishing means to oneposition to permit fluid flow between said lands to said firstrestriction means during the interchange from said first to said seconddrive ratio establishing means and being movable to another position toalign one of said lands with flow from said source to prevent fluid flowto said first restriction during a third to second drive ratioestablishing means interchange; and second restriction means in parallelwith said first restriction means and cooperating therewith forcontrolling the engagement time of said second drive ratio establishingmeans during the first to second drive ratio establishing meansinterchange, and being operable to control the engagement time of saidsecond drive ratio establishing means during the interchange from saidthird to second drive ratio establishing means.
 6. A transmission andcontrol comprising in combination, planetary gearing means; first,second and third fluid operated selectively operable drive ratioestablishing means operatively connected with said planetary gearingmeans for selectively establishing first, second and third drive ratiostherein; a source of fluid pressure; shift valve means in fluidcommunication with said source and said drive ratio establishing meansfor selectively engaging and disengaging said drive ratio establishingmeans; first timing control means in series with said shift valve meansand said second drive ratio establishing means for controlling theengagement time of said second drive ratio establishing means during theinterchange from said first to said second drive ratio establishingmeans; trimmer valve means in fluid communication with said source andsaid first drive ratio establishing means including valve means having apair of spaced lands and being movable to one position in response tofluid pressure in said first drive ratio establishing means to permitflow between said lands from said source to said first timing controlmeans, and to another position when said first drive ratio establishingmeans is inoperative to align one of said lands between said source andsaid first timing control means to prevent fluid flow from said sourceto said first timing control means; second timing control means inparallel with said first timing control means and cooperating therewithfor controlling the engagement time of said second drive ratioestablishing means during the first to second drive ratio establishingmeans interchange, and being operable to control the engagement time ofsaid second drive ratio establishing during the interchange from saidthird to second drive ratio establishing means; and one way valve meansfor permitting free exhaust of said second drive ratio establishingmeans during the second ratio to first ratio interchange and the secondratio to third ratio interchange.
 7. A transmission and controlcomprising in combination; multispeed drive ratio means for providinglow, intermediate and high drive ratios and a plurality of fluidoperated means selectively operated for establishing said drive ratios;a source of fluid pressure; shift valve means, including low,intermediate and high passage means connected to said fluid operatedmeans, for selectively exhausting and connecting said source to saidlow, intermediate and high passage means and said fluid operated meansto selectively disestablish and establish said low, intermediate andhigh drive ratios; variable flow restriction means in said intermediatepassage means having a low and a high restriction position controllingthe time of establishment of said intermediate drive ratio; trimmerregulator valve means operatively connected to another of said passagemeans having a normal position when said another of said passage meansis conditioned to disestablish another drive ratio and operative inresponse to change of fluid pressure in said another of said passagemeans to variably regulate the pressure in said another of said passagemeans for gradual establishment of said another drive ratio while movingto a terminal position and to remain in said terminal position whilesaid another drive ratio remains established and operative duringdisestablishment of said another drive ratio to slowly move from saidterminal position to said normal position and operatively connected tosaid variable flow restriction means and responsive to said movementbetween said terminal and normal positions to provide said highrestriction during a high to intermediate interchange and said lowrestriction during a low to intermediate interchange.
 8. A transmissionand control comprising in combination; multispeed drive ratio means forproviding low, intermediate and high drive ratios and a plurality offluid operated means selectively operated for establishing said driveratios; a source of fluid pressure; shift valve means, including low,intermediate and high passage means connected to said fluid operatedmeans, for selectively connecting said source to supply fluid to saidlow, intermediate and high passage means and said fluid operated meansto selectively establish said low, intermediate and high drive ratios ina predetermined time period and selectively exhausting fluid from saidlow, intermediate and high passage means and said fluid operated meansto selectively disestablish said low, intermediate and high driveratios; variable flow restriction means in said intermediate passagemeans having a low and a high restriction position controlling the rateof flow to and the time of establishment of said intermediate driveratio; trimmer regulator valve means operatively connected to another ofsaid passage means having a normal position when said another of saidpassage means is exhausted to disestablish another drive ratio andoperative in response to the supply of fluid pressure in said another ofsaid passage means to regulate the pressure in said another of saidpassage means at gradually increasing pressures for gradualestablishment of said another drive ratio while moving to a terminalposition and to remain in said terminal position providing full pressurewhile said another drive ratio remains established and operative onexhaust of pressure in said another passage means for disestablishmentof said another drive ratio to slowly move from said terminal positionto said normal position in a time period at least as large as saidpredetermined time period for establishment of said intermediate ratioand operatively connected to said variable flow restriction means andresponsive to said movement between said terminal and normal positionsto provide said high restriction during a high to intermediateinterchange and said low restriction during a low to intermediateinterchange.